The invention relates to a dye auxiliary for sewage-free nanometer printing and dyeing and a preparation method thereof. Each 100 parts of the dye auxiliary includes, by weight, 2-8 parts of diethylene glycol, 0.5-1.5 parts of N-cyclohexylpyrrolidone, 2-6 parts of sodium sulphate powder, 1-5 parts of a dispersant, 0.5-5 parts of a chelating agent, 0.5-2 parts of a non-ionic penetrant, 0.3-1.5 parts of a PH stabilizer, 0.5-3 parts of pectinase, 0.2-2 parts of lecithin and the balance deionized water. Specifically the preparation method includes the following preparation steps of S1, ingredientpreparation; S2, base liquid preparation, wherein deionized water, diethylene glycol and N-cyclohexylpyrrolidone are added to a reaction vessel and stirred well; S3, ingredient adding and mixing, wherein sodium sulphate powder, the dispersant, the chelating agent and the non-ionic penetrant are added in order and well stirring is conducted, then pectinase and lecithin are added and well stirring is conducted, and finally the PH stabilizer is added and well stirring is conducted; S4, auxiliary preparation, wherein well-mixed stirred solution is left to stand for 15-20 minutes to obtain the dyeauxiliary. The dye auxiliary for sewage-free nanometer printing and dyeing has the effect of improving the dispersion stability of dispersed dye particles.